There have been many approaches for inhibiting the activity of viruses such as the human immunodeficiency virus (HIV), herpes simplex virus (HSV), human cytomegalovirus (HCMV) and influenza. Such prior art methods include nucleoside analogs (e.g., HSV) and antisense oligonucleotide therapies (e.g., HIV, influenza).
Prior attempts to inhibit HIV by various approaches have been made by a number of researchers. For example, Zamecnik and coworkers have used phosphodiester antisense oligonucleotides targeted to the reverse transcriptase primer site and to splice donor/acceptor sites, P. C. Zamecnik, J. Goodchild, Y. Taguchi, P.S. Sarin, Proc. Natl. Acad. Sci. USA 1986, 83, 4143. Goodchild and coworkers have made phosphodiester antisense compounds targeted to the initiation sites for translation, the cap site, the polyadenylation signal, the 5' repeat region and a site between the gag and pol genes. J. Goodchild, S. Agrawal, M. P. Civeira, P. S. Sarin, D. Sun, P. C. Zamecnik, Proc. Natl. Acad. Sci. U.S.A. 1988, 85, 5507. Agrawal and coworkers have used chemically modified antisense oligonucleotide analogs targeted to the cap and splice donor/acceptor sites. S. Agrawal, J. Goodchild, M. P. Civeira, A. H. Thornton, P. S. Sarin, P. C. Zamecnik, Proc. Nat'l Acad. Sci. USA 1988, 85, 7079. Agrawal and coworkers have used antisense oligonucleotide analogs targeted to the splice donor/acceptor site inhibit HIV infection in early infected and chronically infected cells. S. Agrawal, T. Ikeuchi, D. Sun, P. S. Sarin, A. Konopka, J. Maizel, Proc. Natl. Acad. Sci. U.S. A. 1989, 86, 7790.
Sarin and coworkers have also used chemically modified antisense oligonucleotide analogs targeted to the HIV cap and splice donor/acceptor sites. P. S. Sarin, S. Agrawal, M. P. Civeira, J. Goodchild, T. Ikeuchi, P. C. Zamecnik, Proc. Natl. Acad. Sci. U. S. A. 1988, 85, 7448. Zaia and coworkers have also used an antisense oligonucleotide analog targeted to a splice acceptor site to inhibit HIV. J. A. Zaia, J. J. Rossi, G. J. Murakawa, P. A. Spallone, D. A. Stephens, B. E. Kaplan, J. Virol. 1988, 62, 3914. Matsukura and coworkers have synthesized antisense oligonucleotide analogs targeted to the initiation of translation of the HIV rev gene mRNA. M. Matsukura, K. Shinozuka, G. Zon, Proc. Natl. Acad. Sci. USA 1987, 84, 7706; R. L. Letsinger, G. R. Zhang, D. K. Sun, T. Ikeuchi, P. S. Sarin, Proc. Natl. Acad. Sci. U.S.A. 1989, 86, 6553. Mori and coworkers have used a different antisense oligonucleotide analog targeted to the same region as Matsukura. K. Mori, C. Boiziau, C. Cazenave, Nucleic Acids Res. 1989, 17, 8207. Shibahara and coworkers have used antisense oligonucleotide analogs targeted to a splice acceptor site as well as the reverse transcriptase primer binding site. S. Shibahara, S. Mukai, H. Morisawa, H. Nakashima, S. Kobayashi, N. Yamamoto, Nucl. Acids Res. 1989, 17, 239. Letsinger and coworkers have synthesized and tested a oligonucleotide analogs with conjugated cholesterol targeted to a splice site. K. Mori, C. Boiziau, C. Cazenave, Nucleic Acids Res. 1989, 17, 8207. Stevenson and Iversen have conjugated polylysine to antisense oligonucleotide analogs targeted to the splice donor and the 5'-end of the first exon of the HIV tat gene. M. Stevenson, P. L. Iversen, J. Gen. Virol. 1989, 70, 2673. Buck and coworkers have described the use of phosphatemethylated DNA oligonucleotides targeted to HIV mRNA and DNA. H. M. Buck, L. H. Koole, M. H. P. van Gendersen, L. Smith, J. L. M. C. Green, S. Jurriaans and J. Goudsmit, Science 1990, 248, 208-212. These prior attempts at inhibiting HIV activity have largely focused on the nature of the chemical modification used in the oligonucleotide analog.
Guanosine nucleotides, both as mononucleotides and in oligonucleotides or polynucleotides, are able to form arrays known as guanine quartets or G-quartets. For review, see Williamson, J. R., (1993) Curr. Opin. Struct. Biol. 3:357-362. G-quartets have been known for years, although interest has increased in the past several years because of their possible role in telomere structure and function. One analytical approach to this area is the study of structures formed by short oligonucleotides containing clusters of guanosines, such as GGGGTTTTGGGG (SEQ ID NO: 1), GGGTTTTGGG (SEQ ID NO: 2), UGGGGU, GGGGGTTTTT (SEQ ID NO: 3), TTAGGG, TTGGGG and others reviewed by Williamson; TTGGGGGTT described by Shida et al. (Shida, T., Yokoyama, K., Tamai, S., and J. Sekiguchi (1991) Chem. pharm. Bull. 39:2207-2211), among others.
It has now been discovered that in addition to their natural role (in telomeres, for example, though there may be others), oligonucleotides which form G-quartets and oligonucleotides containing clusters of G's are useful as drugs for inhibiting viral gene expression or viral growth and for inhibiting PLA.sub.2 enzyme activity, and may be useful as modulators of telomere length. Chemical modification of the oligonucleotides for use as drugs is desirable and, in some cases, necessary.
Guanosine-rich oligonucleotides have been observed in superstructures formed by G-rich oligonucleotides with terminal guanosines. Lu, M., Guo, Q. & Kallenbach, N. R. (1992) Biochemistry 31, 2455-2459; Sen, D. & Gilbert, W. (1992) Biochemistry 31, 65-70. The role of the multimeric structures in antiviral activity is not known and the structures were not characterized further.
Oligonucleotides containing only G and T have been designed to form triple strands with purine-rich promotor elements to inhibit transcription. These triplex-forming oligonucleotides (TFOs), 28 to 54 nucleotides in length, have been used to inhibit expression of the oncogene c-erb B2/neu (WO 93/09788, Hogan). Amine-modified TFOs 31-38 nucleotides long have also been used to inhibit transcription of HIV. McShan, W. M. et al. (1992) J. Biol. Chem. 267:5712-5721. Although each of the above publications have reported some degree of success in inhibiting some function of the virus, a general therapeutic scheme to target HIV and other viruses has not been found.
Accordingly, there has been and continues to be a long-felt need for the design of compositions which are capable of effective, therapeutic use. The present invention is directed to meeting these and other important needs.